[syslinux] Is it possible to replace bios interrupt with a com32 program?

[H. Peter Anvin]

Murali (முரளி கணபதி) wrote:
> On Wed, Mar 19, 2008 at 5:42 AM, H. Peter Anvin <hpa at zytor.com> wrote:
>> louis_fang wrote:
>>  > Hi :
>>  >
>>  > Is it possible to replace bios interrupt with a com32 program?
>>  >
>>
>>  I'm not sure what you're asking here, but from a com32 program you can
>>  access BIOS interrupts via the __intcall() function, unless there is
>>  already a better replacement in the com32 library.  Note that any memory
>>  that is to be accessed as segment:offset will need to be copied to the
>>  com32 bounce buffer (__com32.cs_bounce).
>>
> 
> I think what fang wants is to write a TSR via COM32, so that one COM32
> can be executed and stay in memory (replacing the implementation of an
> existing interrupt), while another COM32 can run and do stuff as
> usual.
> 

Ah.  No, that isn't supported.  Having multiple modules in memory at the 
same time would be a good thing, and is on my long-term list of things 
to do.  However, that would still not be effective once syslinux stops 
running.

If what you're interested in is hooking an interrupt before the 
operating system runs, you need the kind of machinery that MEMDISK 
contains; it might be useful to crib code from (subject to the GPL, of 
course.)

	-hpa